四唑负离子与脒正离子复合物稳定性的理论研究

采用密度泛函B3LYP/6-31+G(d,p) 方法和自洽反应场极化连续模型(PCM)研究四唑负离子与脒类(乙脒或苄脒)正离子形成的两种形式的复合物(末端和侧端)及甲酸根负离子与脒类(乙脒或苄脒)正离子形成的复合物在气相和二甲亚砜（DMSO）溶剂中的稳定性。在气相中，四唑-乙脒和四唑-苄脒复合物的相互作用能(∆E)末端分别比侧端的大3.56和3.72 kJ/mol，表明末端复合物稍占优势。甲酸与乙脒和苄脒的复合物的相互作用能(∆E)分别比四唑与乙脒和苄脒的复合物的大59.35和58.99 kJ/mol，表明脒与甲酸形成复合物时相互作用更强。溶剂DMSO的作用使得所有复合物的相互作用能变小，但脒与四唑的相互作用仍比脒与甲酸的弱。前者的结合常数与后者的相比只有1/315（乙脒）和1/218（苄脒），这与实验结果相一致。

Theoretical Study on the Stability of Anionic Tetrazolate Complexes with Amidiniums

The B3LYP/6-31+G(d,p) level of theory and the polarizable continuum model (PCM) are employed to study the binding interactions between amidinium (acetamidinium or benzamidinium) and tetrazolate anion which have two binding modes (side-on and end-on) as well as the binding interaction between amidinium (acetamidinium or benzamidinium) and formate anion. We find, in the gas phase, that the end-on acetamidinium tetrazolate is more stable with its interaction energy 3.56 kJ/mol higher than that of the side-on. The end-on benzamidinium tetrazolate is more stable with its interaction energy 3.72 kJ/mol higher than that of the side-on. This means the end-on complexes are dominant. The interaction energies of acetamidinium and benzamidinium complexes with formate are higher than those of acetamidinium and benzamidinium complexes with tetrazolate by 59.35 and 58.99 kJ/mol, respectively, indicating that the interactions between amidiniums and formate are stronger than those between amidiniums and tetrazolate. The solvent effect of DMSO decreases the interaction energies in all complexes. However, in this case, the interaction between amidiniums and tetrazolate is still weaker than that in amidinium complexes with formate.